Diagnostic Yield in Families to Sudden Cardiac Death Victims - A 10-year Follow-up Study

AIMS: Up to 70% of sudden cardiac death (SCD) cases in younger individuals are potentially caused by an inherited heart disease. However, long-term diagnostic yield and risk of cardiac events in SCD relatives remain unclear. This study aimed to determine the 10-year diagnostic yield of inherited heart diseases and frequency of cardiac events in SCD relatives.

METHODS AND RESULTS: This retrospective study included SCD probands and their relatives referred to the Unit for Inherited Heart Diseases at Rigshospitalet, Denmark, from 2005 to 2018. Relatives underwent guideline-recommended screening and follow-up. Diagnoses and cardiac events, such as new-onset reduced left ventricular ejection fraction ≤45%, sustained ventricular tachycardia, appropriate implantable cardioverter-defibrillator therapy, cardiac death, and (aborted) SCD, were registered. A total of 686 relatives (47% males, median baseline age 35 years) to 299 probands (75% males, median death age 41 years) were followed for a median of 10.6 years. At 10-year follow-up, 12% of relatives (n = 82) were diagnosed with an inherited heart disease, with 93% (n = 76) diagnosed within 5 years. Cardiac events occurred in 18 (3%) and 24 (4%) relatives after 5- and 10-year follow-up, respectively. Five (0.7%) relatives of probands with no established diagnosis, who had no diagnosis nor cardiac event within 5 years of follow-up, were diagnosed between >5 and 10 years of follow-up.

CONCLUSION: Long-term follow-up identified an inherited heart disease in 12% of SCD relatives, primarily diagnosed within 5 years. Cardiac events were rare (4%). These findings suggest that follow-up may be considered limited to 5 years for specific adult SCD relatives.